I run a cold manifold...but I don;t drive in the winter. ( and my engine combo is much more radical and racey..
(its very drivable and smooth 'cause I spent the time to dial it all in.)

On your car....I would start with one side blocked off and one
side with a 1/2" hole in the intake gasket so you have a "warm manifold"... A warm manifold is easier to tune correctly. A Hot manifold, too hot is a pain..(full open heat risers).. a cold manifold is harder to tune for especially this time of year.j

Its all about finding the sweet spot.

Yah, in had verified with a stop my tdc awhile ago, all was good there. This is about as much cold as the car will see, bout 5° and it seems to run fantastic with the riser blocked. No vacuum leaks, headlight leaks were many when i first got it home and that was the first thing I addressed.